Large Gold Nuggets Part 2
The metal detector used to find the 1.5kg gold nugget was a Minelab GP3000.
Due to a high specific gravity of gold and millions of years of erosion and concentration, gold nuggets have found the lowest possible place to rest. New technology such as Dual Voltage Technology (DVT) is helping prospectors to balance out the ground noise and find nuggets much deeper than before. Even in areas that where previously mined or detected many times before in the past.
Metal detectors may react to iron ores, magnetic non-conductive minerals and beach salts. These non-metallic substances are known as mineralized ground and cause a detector to produce a false signal or ground noise. To eliminate this ground noise, metal detectors have a ground balance function to compensate for the levels of substances in the ground being searched.
The Minelab GP3000 uses DVT. By using two different voltages the possibilities of magnetic saturation of the ground is lessened. Thus, detectors using DVT have an increased ability to balance out ground mineralization providing increased depth and greater sensitivity compared with older detectors. You can learn more about the technology here.
GP3000 metal detectors cost between $3000US and $3650US, you can buy one here.
It might be worth looking on ebay for a second hand Minelab Metal Detector, I'm sure plenty of people get bored with them after they don't find any big nuggets in the first few months. Keep in mind that this man had been prospecting for 20 years!